The present invention relates to novel s-triazolo[3,4-i]purine derivatives which possess a broncho-dilatory activity, diuretic activity, renal protecting activity and/or anti-amnestic activity.
As s-triazolo[3,4-i]purine derivatives represented by the following formula: ##STR3## 9H-s-triazolo[3,4-i]purine which has no substituents at the 3-, 5-, 7- and 8-positions and s-triazolo[3,4-i]purine derivatives which have benzyl at the 7- or 9-position are disclosed in J. Org. Chem., 30, 3601 (1965); and 3- alkylthio-s-triazolo[3,4-i]purine having SH, SCH.sub.3 or SCH.sub.2 CONH.sub.2 at the 3-position is disclosed in Aust. J. Chem., 35, 1263 (1982). As yet their pharmacological activities are unknown. Furthermore, s-triazolo[3,4-i]purine derivatives having a substituent at the 5-position thereof have not been reported so far.